A laser designator receiver is one mechanism for guiding a missile or other laser-guided munition to a desired target. A laser designator receiver includes a plurality of detector elements, typically at least four detector elements, arranged in a two-by-two grid located in a body of the munition. The laser designator receiver operates in response to electromagnetic radiation (EMR) reflected by the desired target that is received through a window in the nose cone, passed through one or more optical elements, such as a lens arrangement, and then received by the grid of detector elements.
The shape of the nose cone plays a substantial role in the speed and range of a munition. Preferably the shape of a nose cone is as aerodynamic as practicable, to increase range and/or speed of the munition. Unfortunately, a hollow conical nose cone induces substantial distortions in the EMR received through the surface of the nose cone. These distortions reduce the accuracy of the munition and, in some situations, can render the guidance system inoperable. Efforts have been made to design optical systems that correct such distortions prior to passing the EMR to the laser designator receiver, but such optical systems are complex, increasing cost, adding weight to the munition, decreasing munition range and speed, and increasing the number of components that can fail in the munition.
Consequently, to avoid the issues associated with hollow conical nose cones, the window of a conventional laser-guided munition has a relatively thin spherical surface to reduce the distortion of the EMR passing through the window into the munition. Unfortunately, a spherical surface is not an aerodynamic shape and negatively impacts range and speed of the munition.